Guitar machine



March 11, 1969 J. B. THOMPSON I 3,431,807

GUITAR MACHINE Filed April 7, 1967 15 2 2 a F! 8 I8 Iii Iv/11111111114 V I 12- 7 [m 1 l INVENTOR.

, 1 Josepuus B. THOMPSON y w iww ATTORNEY I United States Patent 2 Claims Int. Cl. G10d 3/14 ABSTRACT OF THE DISCLOSURE A guitar machine having novel supporting structure associated with its worm and gear elements.

This invention relates to guitars, and particularly to a guitar machine for tuning the strings thereof.

The primary object of the invention is to provide a guitar machine having supporting bearing surfaces for its worm body, as well as for the worm and gear shafts.

Another object is to provide a guitar machine having perfect meshing of its worm and gear, assuring no backlash or slippage and a lifetime of trouble-free operation.

These, and other objects of the invention will become apparent from a reading of the following specification and claims together with the accompanying drawing, wherein like parts are referred to and indicated by like reference numerals, and wherein:

FIGURE 1 is a front elevational view of the guitar machine that is the subject of this invention;

FIGURE 2 is a left end elevational view;

FIGURE 3 is an exploded view of the housing, showing the case and base elements in their un-assembled condition;

FIGURE 4 is a top plan view of the case;

FIGURE 5 is a sectional view of the case, taken along the line and in the direction of arrows 5--5 of FIG- URE 4;

FIGURE 6 is a longitudinal section-a1 view of the assembled guitar machine with the tuning post in elevation;

FIGURE 7 is a sectional view taken along the line and in the direction of the arrows 7-7 of FIGURE 6, with the gear, worm and worm shaft in elevation;

FIGURE 8 is a side elevational view of the string post in its unmounted condition;

FIGURE 9 is a sectional view taken along the line and in the direction of arrows 9-9 of FIGURE 10; and

FIGURE 10 is a top plan view of the base plate.

Referring more particularly to the drawing, there is seen in FIGURE 1 the guitar machine, that is the subject of this invention, broadly indicated by reference numeral 10, having a hollow worm and gear case 11 mounted on a base plate 12 by means of four pins 16 fitted through counter-sunk holes 17 in the base plate 12.

The case is locked to the base by spinning the ends of the pins 16 until they fill the counter-sink of the holes 17 flush with the rear face of the base plate 12, as seen in FIGURE 6.

The base plate 12 has two upstanding, spaced and aligned lugs 19 and 20, having aligned end faces curved to define half-bearing surfaces for the worm shaft 26.

Reference numeral 21 indicates a tuning post collar mounted on the lower side of the base plate, with a 1 /2 tapered bearing bore 22 centered therethrough, as is seen most clearly in FIGURE 9.

As seen most clearly in FIGURES 3, 4 and 5, the hollow case 11 has two opposed and aligned slots 13 and 14, cut in its side walls, of a width to receive the base lugs 19 and 20, respectively, therein.

Each slot is shaped, at its inner end, to define halfbearing surfaces for the worm shaft 26, which co-operate with the half-bearing surfaces of the lugs 19 and 20, when 3,431,807 Patented Mar. 11, 1969 fitted therewith, to define full-bearing mounts for said shaft.

Reference numeral 15 indicates a continuous bearing surface extending cross-wise of the case end wall, at the bearing slots 13-14, having a curvature matching that of the worm 27 to provide a support for the worm 27 the entire length thereof, against lateral thrust, as seen in FIGURES 6 and 7.

Referring again to FIGURE 8, the tuning post 24 has a worm gear 23 mounted at one end thereof and a string anchoring hole at the other end.

Section 25 of the post 24, immediately adjacent the gear 23, has a I A2 taper and is adapted to be journaled in the mating tapered bearing bore 22 of the collar 21, as seen in FIGURE 6.

The guitar machine 10 is assembled by positioning the worm shaft 26 in the bearing slots 13 and 14, with the worm 27 journaled against the case bearing surface 15.

The string, or tuning, post 24 is journaled through the collar 21 of the base plate 12, with the shoulder 29 of the gear 23 positioned against the inner end of the collar 21, as seen in FIGURE 6, and with the post tapered section 25 fitted in the mating tapered bearing 22 of collar 21.

The base plate 12 is then placed against the case 11 with its bearing lugs 19 and 20 inserted in the case bearing slots 13 and 14, against the worm shaft 26, on either end of the worm 27, and with the case mounting pins received through the base plate mounting holes 17. At the same time the teeth of the gear 23 will engage the teeth of the worm 27, as seen again, in FIGURES 6 and 7.

The ends of the pins 16 are then spun to fill the countersink of the holes 17, to lock the case to the base 12, forming the completed guitar machine 10.

The guitar machine 10 is mounted on the neck of the guitar by means of screws passed through the mounting holes 1 8 of the machine base 12.

The string post 24 is rotated by grasping the thumb button 28 of the worm shaft 26 and rotating same in the conventional manner to vary the tension of the string anchored to the tuning post 24, not illustrated.

The mating tapered configuration of the post bearing section 25 and the collar bearing bore 22 assure true rotation of the post 24, even after long use, since any end thrust against the post acts to maintain a perfect fit between the opposed tapered journal surfaces 25 and 22.

Again, any lateral thrust against the rotating worm 27, due to the normal reaction of the forces between the inter-meshed gear 23 and worm 27 is born by the bearing surface 15, in addition to the bearing surfaces 13-19 and 14-20 of the worm shaft 26.

Thus wear of the worm shaft bearings is prevented, assuring no back-lash or slippage between the meshed worm and gear, no matter how often the tuning operation is repeated.

It will now be clear that there has been provided a device which accomplishes the objectives heretofor set forth.

While the invention has been disclosed in its preferred form, it is to be understood that the specific embodiment thereof as described and illustrated herein is not to be construed in a limited sense.

I claim:

1. A guitar machine, comprising in combination:

'( a) a flat base plate;

(b) two spaced and aligned upstanding lugs mounted on the top-side of the base, having half-bearing surfaces at their upper ends;

(0) a depending string post collar mounted on the underside of the base, spaced longitudinally of the lugs, having a tapered bearing bore centered therethrough;

(d) a hollow case mounted on the top-side of the base, having top, side and end walls, the side walls having slots cut therein with half-bearing surfaces at their inner ends, adapted to receive the base lugs therein and co-0perate therewith to provide full bearings for the shaft of a worm journaled in the case therebetween;

(e) a string tensioning thumb button mounted on the worm shaft;

(f) a continuous bearing surface extending across one end wall of the case in contact with the peripheral surface of the worm, the length thereof, to support the worm against lateral thrust, and having a common center with the worm shaft bearings;

(g) a string post, having a tapered section journaled in the collar tapered bearing bore; and,

(h) a gear mounted at the end of the string post, in-

side the case, in mesh with the worm and driven by rotation of the worm.

2. A guitar machine, as in claim 1, in which the taper of the mating journal surfaces of the string post and its mounting collar is 1 /2 References Cited UNITED STATES PATENTS 15 RICHARD B. WILKINSON, Primary Examiner.

G. M. POLUMBUS, Assistant Examiner.

U .8. C1. X.R. 

